Back-to-back e&m T1 for testing

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Oct 9th, 2007
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I am trying to route calls over a "hairpinned" T1 on a 2811 router between two MFT-1T1 ports. Works great with PRIs, but I can't get a CAS E&M trunk to work. I know that analog E&M can be tested this way by using a rollover cable with the type that is symmetrical.

I have used "debug vpm all", and the destination side sees a seizure, but I don't see it "wink". The calling side has a 550msec timer, and times out waiting for the wink, so no digits get passed. I am using H.323 with CallManager, and IOS 12.4(15)T1.

Should this work, or am I missing something?

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paolo bevilacqua Wed, 10/10/2007 - 01:58
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which IOS are you using and config? Things are supposed to work as you said, problem is, sometime they don't.

dgahm Wed, 10/10/2007 - 08:44
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I have seen some flakiness with CAS T1s on 2800 routers. A reload of the router usually fixes it.


bgrunewald Wed, 10/17/2007 - 03:17
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Reload did not help. I also tried FXO to FXS and using E&M Immediate Start on both sides. None of them work, and my reading of the debugs makes it look like one side isn't seeing the signaling bits and never responds to the off hook from the initiating side. Not sure where to go with it from here, but I had to switch back to PRI to get some testing done.


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